In certain processes, such as, for example, manufacturing or analytical or diagnostic testing processes, it is often necessary, or at least desirable, to identify an article or item undergoing a process and to monitor the location and status of the article throughout the process. This may especially be the case in automated processes that involve multiple steps performed at multiple locations throughout a system, e.g., an assembly line, a fabrication line, diagnostic instrument, or a laboratory. It is also not uncommon that one or more process steps performed may need to be varied for different articles and thus it becomes necessary to not only track the location of the article but to also communicate to different processing modules within the system the particular step or steps to be performed on that particular article.
For example, in analytical or diagnostic chemical or biological tests, such as molecular diagnostic assays, the nature and/or source of a sample to be tested and/or the specific test protocols to be followed in testing each sample must be monitored and tracked throughout the testing process.
In the case of chemical or biological testing, identification of the sample, e.g., the nature and/or source, including clinical, industrial, environmental, and food sources, of the sample, may be implemented by means of a label bearing identifying information placed on a container that holds a volume of sample from which aliquots of the sample are taken for testing and/or a container within which one or more chemical or biological reactions are to take place. Such identifying information may include human-readable (e.g., alphanumeric) information to be read by persons handling and processing the container. For containers that are to be placed into a diagnostic instrument for subsequent automated processing, it is may be advantageous to provide machine-readable information on the container. Such machine-readable information may include a barcode (linear or 2-dimensional) that can be read by scanners within the instrument or laboratory and wherein the unique number sequence that is encoded in the barcode is correlated with an information record, e.g., via a relational database, relating to the container and/or its contents. For biological samples, the information may comprise the nature of the sample material, e.g., blood, urine, sputum, saliva, pus, mucous, cerebrospinal fluid, fecal matter, etc., the source of the sample material, e.g., a patient name, and the test or tests to be performed on the sample material. As the container is being processed within an instrument and/or a laboratory, data from the container barcode is read by a barcode scanner, or reader, and data encompassing (or otherwise containing) information derived from the barcode data, as well as, optionally, data encompassing other information associated with the barcode information, can be written to or retrieved from memory to be readable by a processing instrument. During or after the process, additional information may be added to the record, including, for example, tests or processes to be performed, test results and error codes, available volume in container, instrument IDs, and/or other tracking information, such as a complete history of all instruments on which the container has been processed.
In one embodiment, the data of the container barcode constitutes an address in a database, e.g., a relational database, within which information regarding the contents of the container is stored. For example, if the container holds a sample, the information contained in the barcode data may be used to look up in a database information regarding the sample, such as the nature of the sample (blood, urine, etc.), the identity of the patient, or other source, from which the sample was obtained, the date the sample was obtained, the test(s) or assay(s) to be performed on the sample, etc., or a combination thereof. On the other hand, if the container contains reagent or some other process material, information contained in the barcode data may be used to look up in a database information regarding the type of process material, manufacturer, lot number, expiration date, storage conditions, history of use, volume, etc.
In some cases, empty containers may be provided that are pre-labeled with unique identifying information, such as a barcode, and that unique identifying information is later associated with information relating to the sample that is placed into the container. The association may be made by scanning the pre-applied barcode and associating the information encoded in the barcode with information relating to the sample material added to—or to be added to—the container. In other instances, before or after sample material is placed in an unlabeled container, a label may be printed for that container bearing a unique identifier that has been associated with information relating to the sample material placed in the container. Such labels are typically printed onto adhesive-backed paper, and a technician or other laboratory personnel will peel the label from its backing and place it on the container. Care must be taken to ensure that the label is placed on the container at the correct orientation to enable the label code to be read by a scanner and to ensure that the printed information on the label is not smudged or otherwise distorted, e.g., by a wrinkle in the label, in a manner that will interfere with subsequent reading of the label. Needless to say, care must also be taken to ensure that each label is placed on the correct container containing the sample material associated with the unique identifier on the label.
To avoid the need for laboratory personnel to peel labels from the backing and to reduce the possibility of misapplied or unreadable labels, it may be desirable to print the unique identifying information directly onto an initially-blank label placed on the container. In the case of machine-readable information, such as barcodes, the printed information must be sufficiently precise to enable the information to be accurately read by barcode scanners. A poor quality print e.g., faint, blurred, or fuzzy lines and edges or characters running together—will impair the ability of a scanner to accurately read the information printed on the label. Typically, thermal printers, which produce an image by selectively heating coated thermo chromic paper, or thermal paper, when the paper is passed over a thermal print head, are best suited for such applications because they are capable of clean, precise printing. In addition, in chemical or biological laboratory applications, as well as in specialized, e.g., clean room, fabrication, or assembly processes, thermal printers are advantageous over other printers that use inks or carbon-based toner powders because such inks or powders can be a source of contamination in the process. In addition, the lack of consumables, such as ink, ribbons, toner, etc. associated with other printers, improves the reliability of thermal printers over such other printers and makes thermal printers easier to use and maintain as the necessary servicing of such non-existent consumables is avoided.
Precise printing with a thermal printer requires sufficient physical and thermal contact between the thermal print head and the thermal paper throughout the printing process, which involves relative movement between the print head and the paper. Where the surface to be printed on is curved and/or is subject to imperfections or other surface anomalies, such as warpage, bumps, rippling, bowing, etc., maintaining such contact can be extremely difficult, especially where the surface to be printed on is relatively hard and rigid. In conventional thermal printers, such as point of sale printers, the print head contacts the thermal paper, as the paper moves over a roller, that is typically made from an elastomeric material, such as rubber. As the surface of such a roller will be compliant, the print head can press the thermal paper against the roller surface, and the compliance of the roller surface facilitates uniform contact between the print head and the paper. In addition, rollers for such printers can be made with tight tolerances so as to minimize dimensional variations and surface anomalies. On the other hand, containers used in certain chemical or biological tests may comprise generally cylindrical tubes made from an injection-molded thermoplastic. Such tubes may be of a relatively small diameter, e.g., 0.5 inches, and thus the side wall of such tubes have a high degree of curvature. Moreover, by the very nature of the molding process when articles of this type are mass-produced, such tubes may have dimensional tolerances that lead to concave and/or convex side wall portions that can create high points or low points or other surface imperfections and anomalies that inhibit good, uniform contact between the thermal print head and the side wall of the tube.
Thus, a need exists for a device configured to print—especially thermal print—information onto a curved surface that may include dimensional inconsistencies and other inconsistent and unpredictable surface variations and anomalies.